How Did Some Ancient Humans Get Blue Eyes?

Where blue eyes come from is usually answered with one mutation, in one person, somewhere between 6,000 and 10,000 years ago. Ancient DNA has pushed blue eyes back to at least 12,000 years ago, and the single-ancestor claim turns out to rest on 155 Danes and a press release. 0:00 Where Blue Eyes Come From 0:24 Blue Eyes Have No Blue Pigment 0:42 Why Blue Eyes Look Blue 1:29 The HERC2 Gene And Eye Colour 1:44 How The OCA2 Switch Works 2:14 The One Ancestor Study 2:50 What That Study Actually Said 3:23 Do All Blue Eyed People Share An Ancestor 4:28 How Old Are Blue Eyes 5:02 Blue Eyes In Hunter Gatherers 5:27 Why Blue Eyes Became Rarer 5:47 Cheddar Man And La Brana 1 6:24 When Europeans Got Pale Skin 6:44 How Ancient DNA Predicts Eye Colour 7:24 Why Blue Eyes Evolved 7:58 Two Blue Eyed Parents, Brown Eyed Child 8:19 Where Blue Eyes Came From, Short Answer 8:38 Are Blue Eyes Disappearing 8:52 What Came Next What You Will Learn In This Video: No Blue Pigment Exists: Your iris can only make melanin, in brown, black and a reddish yellow. Blue eyes are a structure that scatters light, the same effect that makes the sky blue, not a colour anybody has. It Is Not A Pigment Gene: The variant sits in the 86th intron of HERC2, a gene with nothing to do with colour, and works as a long-range switch that dials down OCA2 next door. Turn it down and you get blue. Turn it off and you get albinism. What The Famous Study Really Said: 155 blue-eyed Danes, 5 Turks, 2 Jordanians, a title that says "may be caused by", and no dating analysis anywhere in the paper. The 6,000 to 10,000 year figure comes from the coverage, not the research. Three Haplotypes, Not One: A later look at the same stretch of DNA with finer markers found three distinct haplotypes, different patterns in Europeans and East Asians, and separate OCA2 changes that produce blue eyes only in Scandinavians. Blue Eyes Peaked Before Farming: In 348 ancient Eurasian genomes, light eyes run at roughly a third of Mesolithic hunter-gatherers and fall to about one in eight in the Neolithic. Farmers arrived in numbers and diluted them. Eyes Came Long Before Pale Skin: Cheddar Man and La Brana 1 both had blue eyes and dark skin. Dark or intermediate skin still shows up in about half the individuals sampled into the Bronze and Iron Age. How We Actually Know: The forensic tool used for this was built for living suspects. Below roughly 8x coverage you cannot read genotypes off an ancient genome directly, which is worth remembering before trusting any confident sentence about ancient skin tone. The Punnett Square Is Wrong: A study of nearly 195,000 people found 61 separate regions of the genome affecting eye colour. Two blue-eyed parents can have a brown-eyed child. #AncientHumans #blueeyes #eyes #ancienthistory #eyecolour #Prehistory #Genetics #HumanEvolution #Archaeology